Which statement is most accurate?

Autodesks Official Answer: If on, Maya automatically scales the depth map so that it only fills the area of the light’s illumination that contains shadow casting objects.

For example, if shadow casting objects are only in the center of a spot light’s beam, the depth map only covers the region occupied by those objects. Because the Resolution is an absolute resolution (that is, pixels, not pixels per inch), decreasing the size of the depth map effectively increases the resolution of the depth map and the quality of the shadows without increasing rendering times.

If off, you can manually scale the depth map within the area of the light’s illumination using the Focus attribute (for point lights and spot lights) or the Width Focus attribute (for directional lights). Use Auto Focus is on by default.